Slashdot Mirror
IEEE Seeks For Ethernet To 'Go Green'
alphadogg submitted a piece at the NetworkWorld site about the IEEE's efforts to introduce energy efficiency to Ethernet use. The group's Energy Efficient Ethernet group is looking into methods by which standards can be tweaked to encourage power savings. Current plans include ways to make computers 'choosier' about what level of bandwidth they're using. Idle systems would only run at 10Mbps, while email might draw 100Mbs, and scale up to 1000Mbps for large downloads and streaming video. The group is planning to discuss changes to the Ethernet link and higher layers. No restrictions are planned for device manufacturers, although the article suggests some companies might try to use energy efficiency as a competitive advantage. The EEE group estimates some $450 million a year could be saved via the use of energy efficient Ethernet technology.
Sounds like someone is really starting at the wrong end. IMHO.
I'd estimate that power supply inefficiency chews up more than this proposal will ever save. If you spent your time making the power supplies of PC's, Switches, routers more efficient you'd probably have a greater impact. How about better efficiency in the FET's, transistors and amplifier circuitry? Last time I checked, my Ethernet looms didn't get that hot. (isn't it all about "(i^2).R"?. Heck turning off the light in the switch room probably does more to save power. Plus all the heat im my server room is from the servers, not the Ethernet. If your that worried, switch to fiber.
I thought the transfer of data at the physical layer was through the transfer of 'holes' anyway.
An idea I've always thought about is converting to DC supplies indoors. AC has an advantage in terms of long-distance transmission, but in this day and age a HUGE part of our electric use is in devices that require DC power. Hell, many of the things that run AC (like lights) can in fact run DC with nary a problem. It's always boggled my mind why we have a bajillion power bricks sitting around, each venting heat like mad converting AC/DC, when in fact we could have a much more efficient "main" transformer installed in the house that does it on a larger scale and feeds our devices directly.
I imagine this would be even more useful for heavy power using environments like server farms - imagine if you can do with the huge boxy PSUs in every single box and just have a unified DC power source that can FAR more efficient than what's in the average beige boxen.
I think what they're proposing is clock frequency control for Ethernet chips, like CPUs have now. I read somewhere that the power consumption increases n^3 with the clock speed, dunno where that figure comes from though.
...is this group led by ethernet equipment vendors? Perhaps vendors who are unhappy with the recent decline in equipment upgrades since people aren't upgrading from gigabit or even to gigabit from 100mbit in a way that helps their stock price sufficiently?
It seems to me that, considering the number of ports active out there, they're talking about a tiny amount of savings per port for a total investment that could have a much larger effect if spent elsewhere.
Hell, I bet more power is wasted by the power supplies, overly conservative fan controls, uncleaned air filters, shorted out UPS batteries that should have been replaced decades ago, overpowered CPUs, and crappily written firmware of the currently deployed switches than is consumed by transmission losses.
For broadcom Ethernet PHY chips, they use about 1W/port when configured as 1000BaseT (GigE). GigE require some heavy duty DSP filtering as well as driving 4 pairs of bidirectional transceiver. They would burn less power when they are running at 100BaseT which only to drive 1 pair of receive and transmit. Not sure if there are significant saving going down to 10BaseT as the number of transmit pairs and the DSP's are dominant.
While this might not seem a whole lot of power, when you are looking at Enterprise size (say a few hundreds to thousands ports) setup, there can potentially be savings at the few hundred watts to thousand watts range.
At an office I once worked, there were a lot of spare switches laying about after upgrading to 1000BaseT. They were considered "spare" or whatever, but there was a great many... so I sorta brought one home and mounted it into my rack and used it for a couple of months. The next two electric bills made me rethink how nice it looked to have a 24 port switch in my rack instead of that cheapy 8 port sitting on a shelf. It consumed a NOTABLE amount of power. Now, there were other things involved I'm sure... things like the changes of the seasons, global warming and all that. But when I brought the switch back to the office and went back to my cheapy 8 port again, I saw a change in my power bill.
If I ever decide to spend money on a nice looking switch, I'll be sure to reference the power draw of the units I review.
- it's the power required to process the packets. More or less, a GigE card should need 10X (divided by some fudge factor that probably makes the real ratio closer to 2 or 3X) the compute power of a 100Mbit card. Processing GigE at full throttle actually takes quite a bit of CPU - we don't notice it much because most GigE interfaces have a TCP Offload Engine that avoids bogging down the CPU and bus.
So your TOE could easily have a variable speed CPU that basically goes to sleep when it can negotiate the physical interface down to 10Mbit, or whatever. SOunds pretty straightforward.
Give a man a fish and you have fed him for today. Teach a man to fish, and he'll say "WHERE'S MY FISH, YOU IDIOT?"
The 50V limit was actually put into law by telecom lobbyists. Under 50V, you don't need an electricians license, and they wanted to be able to do telecom work without electricians. 50V, and even 25V can be quite dangerous if you don't pay attention.
My blog. Good stuff (when I remember to update it). Read it.